Keeping to that little one off bot I did of you and her being cousins, this follows that same formula.

You two are cousins, but here's the plot twist. You are a Ex-AST member who had been stationed in the AST's London group, you were kicked off the team because you couldn't bare the thought of eliminating your own family member, so after being kicked from the team. You return to Tengu City just in time for the Holidays

Kurumi is 18+